An agricultural seeding machine such as a row crop planter or grain drill places seeds at a desired depth within a plurality of parallel seed trenches formed in soil. In the case of a row crop planter, a plurality of row crop units are typically ground driven using wheels, shafts, sprockets, transfer cases, chains and the like. Each row crop unit has a frame which is moveably coupled with a tool bar.
In areas where air seeder type equipment is used to seed small grains there has been a significant move to reduce input costs to the seeding process. One way to do this is to adopt no-till farming practices to reduce equipment and fuel costs. Another way is to combine the operations involved in seeding, for example tillage, seed bed preparation, fertilizer and seed placement. A further option is to utilize combined operations in a no-till farming practice.
There are machines presently available that have some ability to combine these operations. These are usually divided into two categories, air hoe drills and air disc drills. The first utilizes a combination of shanks with shovels or boots to create a trench for the seed, basically it ‘hoes’ a trench. Examples of such tools are John Deere 1820, Bourgault 5710, Morris Maxim II, 8900 and 9000, or Case ATX Series. The second type utilizes disc type openers to create the seed trench. Examples of such tools are John Deere 1890, Bourgault 5720, Morris Never Pin or Case SDX Series.
Not all of these machines are capable of placing fertilizer at the same time as seeding. Generally it is easiest to place dry granular fertilizer at the same time as seeding since that type of fertilizer can be distributed by a similar air delivery system. The application of liquid fertilizer requires an additional delivery and distribution system, typically not supplied by the air seeder manufacturer. The application of gaseous fertilizer such as anhydrous ammonia (also referred to as NH3) also requires an additional delivery and distribution system, typically not supplied by the air seeder manufacturer. A further difficulty with NH3 is the requirement to effectively seal the gas into the ground. This is typically the most challenging task for these openers.
To effectively retain the gas in the ground it is necessary to place the gas accurately in a trench and seal it therein. To achieve this it is preferable to create a small, neat trench at constant depth and close the trench quickly and efficiently afterwards. The difficulties encountered with known designs are in all aspects of this operation. Those devices suffer from one or more of the following detrimental actions: 1) too much soil disturbance creating a large trench with soil displaced significantly; 2) lack of depth control; 3) inability to close or seal the trench immediately after release of the gas; and 4) high draft because of the need to place the NH3 at deeper depths.
The most popular method of applying NH3 in the mid-western portion of the U.S.A. is through the use of a shank type opener with two closing disks positioned behind the shank relative to a working direction. NH3 is typically applied in the fall of the year with a shank type opener, resulting in an additional field operation with associated costs. Although these type of openers function well, they require deep (6-10″) application in order to obtain adequate NH3 retention. Application at these depths requires a lot of horsepower and results in a field with noticeable soil disturbance.
In areas where air seeding equipment is used, many farmers are changing from conventional farming to direct or one-pass seeding (placing fertilizer during seeding). These type of air seeders generally use disc openers to apply NH3 because the rate of application is significantly smaller at the time of seeding vs. a fall application. This lower rate allows the use of disc openers that have much less soil disturbance than a traditional shank. One difficulty with these type of openers is the ability to adequately seal the trench and prevent out-gassing due to the shallow depth and formation of a trench. Developing a single disk opener that can adequately apply and retain high rates of NH3 at high speeds and shallow depths would provide farmers and custom applicators with a more productive NH3 applicator than the traditional shank applicator.
What is needed in the art is an opener/closer arrangement which does not open the trench too deep, effectively seals the fertilizer within the trench, effectively closes the trench, and has a low draft at high operating speeds.